The present invention relates to a streaking tube used in a new instrument to measure the multichannel light signals in the time resolving mode.
The configuration of the conventional streaking tube will briefly be described hereafter.
FIG. 1 shows a cross-sectional view of the conventional streaking tube. Slit Sl is arranged on the front panel of camera B in a direction perpendicular to the plane of the drawing. An image formed by the light to be measured is formed when the light beam passes through slit Sl, and it is incident by lens L1 on photocathode Pd of streaking tube S to form a linear image.
Streaking tubes consists of photocathode Pd, mesh electrodes Me, focusing electrodes F, aperture A, deflection electrodes D, microchannel plate M and phosphor layer Ph.
Electrons generated at the photocathode Pd are accelerated by electrostatic field formed with electrodes Me, focused by the static lens formed with focusing electrodes F, and then deflected by the electric field formed within a deflection area defined by deflection electrodes D after passing through aperture A.
The deflected electrons are multiplied by microchannel plate M, and then a streaking image is formed in a direction parallel with the scanning.
The image formed on phosphor layer Ph is transmitted to the photocathode or image target of imaging device Im after passing through lens L2 .
The streaking tube can store with high time resolution the image changing with time at high speed, or the light beam whose intensity may change with time at high speed, and thus it can be used in many applications.
The intensity distribution of the linear light image changing with time, appearing along the slit, is required to be measured when a plurality of light signals is incident on the slit passing through a plurality of optical fibers which are arranged in line along the slit. The following configuration may be required:
First, the optical fibers should be arranged in line along the slit Sl of the streak camera B and the image formed by these optical fibers may be projected onto photocathode Pd of streaking tube S through relay lens L1 .
Second, fibers should be arranged in front of a fiber plate by using the streaking tube with an incident window for the fiber plate, and the light signals to be measured may be incident on the other edges of the fibers.
The former has such disadvantages that the angle of divergence of the light beam transmitted from each optical fiber is wide and that an eclipse can occur when the light beam passes through relay lens L1 . This decreases the efficiency of transmission of the light beam via relay lens L1 .
The latter has such disadvantages that some optical losses are found in a junction between the optical fibers and fiber plate.
Adhesives have been tested to reduce the losses in the junction, but however, no proper material has been found.
Also, in both cases the slit width (10 to 30 .mu.m in normal cases) to determine the time resolution of the streak camera becomes the diameter (50 to 100 .mu.m) of each fiber, and then higher time resolution cannot be obtained.
The fibers and streaking tube in both the former and latter are separatedly provided in a setup of the instrument and alignment of the fibers to the streaking tube is of prime interest.
The instrument to measure the light intensity distribution along the slit is dissatisfactory because the energy losses of the light beam to be measured are greater than those which can be permitted, and because the time resolution, reliability and operationability in measurement are lower than those required by the person skilled in the art.
The objective of the present invention is to present a streaking tube which is suitable for measuring the light signals in a plurality of channels, appearing along the slit arranged perpendicular to the scanning beam on the photocathode of the streaking tube.